Supplementary Information
Efficient Thermolysis Route to Monodisperse Cu2ZnSnS4 Nanocrystals with Controlled
Shape and Structure
Xiaoyan Zhang,1 Guobiao Guo,1 Cheng Ji,1 Kai Huang,1 Chenyang Zha,1 Yifeng Wang,1 Liming Shen,1 Arunava Gupta,2 and
Ningzhong Bao1
1
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing
210009, P. R. China, 2Centre for Materials for Information Technology, University of Alabama,
Tuscaloosa, AL 35487, United States.
Corresponding authors: agupta@mint.ua.edu (AG); nzhbao@njtech.edu.cn (NB)
Content:
Rietveld refinement results, Table S1-4------------------S2-3
Table S5-------------------------------------------------------S4
Figure S1------------------------------------------------------S5
Figure S2------------------------------------------------------S6
Figure S3------------------------------------------------------S7
Figure S4------------------------------------------------------S8
S1
Rietveld refinement results
Rietveld refinement for XRD data of wurtzite-type and kesterite-type structures of
Cu2ZnSnS4 was performed using the program of Rietan-FP [F. Izumi and K. Momma, Solid State
Phenom., 130 (2007) 15-20.], where a modified split pseudo-Voigt function was employed for
the whole range of XRD reflections, with partial profile relaxation applied for some highly
asymmetric profiles. The resultant Rwp values were 10.7 and 11.97 %, respectively.
1. Wurtzite-type Cu2ZnSnS4
Space group: A-186.
Hermann-Mauguin symbol: P63mc.
Table S1: Lattice Parameters
Parameters
Unit
Value
Estimated standard deviations
a
Å
3.80915
2.755885E-03
b
Å
3.80915
2.755885E-03
c
A
b
Å
º
º
6.30026
90.0000
90.0000
2.887705E-03
0.191416
0.142928
g
º
120.000
0.566006
79.1672
0.0888
3
V
Å
Theoretical density: d = Total mass/V = 3.648553E-22/7.916867E-23 = 4.608582 g/cm3
Atom
Zn
Sn
Cu
S
Site
2b
2b
2b
2b
Table S2: Site Parameters
Occupancy
x
y
0.2500
0.33330
0.66670
0.2500
0.33330
0.66670
0.5000
0.33330
0.66670
1.0000
0.33330
0.66670
z
0.00000
0.00000
0.00000
0.37500
B
0.044
0.096
0.693
4.822
Parameter B: isotropic atomic displacement parameter. The occupancy of Zn, Sn, and Cu atoms
is derived based on the ideal composition: Cu2ZnSnS4.
S2
2. Kesterite -type Cu2ZnSnS4
Space group: A-121.
Hermann-Mauguin symbol: I 2m.
Table S3: Lattice Parameters
Parameters
Unit
Value
Estimated standard deviations
a
Å
5.43268
5.147635E-03
b
Å
5.43268
5.147635E-03
c
a
β
Å
º
º
10.7642
90.0000
90.0000
1.354207E-03
0.167954
0.10379
γ
º
90.0000
0.182188
V
Å3
317.6948
0.5839
Theoretical density: d = Total mass/V = 1.885383E-21/3.176948E-22 = 5.934572 g/cm3.
Table S4: Site Parameters
Site/Species
Occupancy
x
y
z
B
Cu1/Cu
0.5
0.0
0.5
0.25
1286.42
Zn1/Zn2+
0.5
0.0
0.5
0.25
1.28954
Cu2/Cu
1.0
0.0
0.0
0.0
92.4028
Sn1/Sn4+
1.0
0.0
0.0
0.5
18.5591
S1/S
1.0
0.764241
0.744635
0.8865
0.69197
S3
Table S5: Composition of CZTS nanocrystals synthesized using different Cu/(Zn+Sn) ratio
of oleate precursor
The Cu/(Zn+Sn)
ratio calculated
based the
precursor
composition
0.5
Cu %
Zn %
Sn %
Cu:Zn:Sn
Cu/(Zn+Sn)
19.65
9.74
18.84
2:0.99:1.92
0.69
0.6
18.51
11.09
16.09
2:1.2:1.74
0.68
0.7
22.18
10.28
14.73
2:0.93:1.33
0.88
0.8
21.77
10.20
12.75
2:0.94:1.17
0.95
0.9
23.68
12.70
13.02
2:1.07:1.1
0.92
1.0
24.95
11.73
12.02
2:0.94:0.96
1.05
1.1
23.94
10.89
13.78
2:0.91:1.15
0.97
1.2
26.83
09.68
12.66
2:0.72:0.94
1.20
S4
XRD patterns of the CZTS nanocrystal synthesized in ODE at temperatures of (a) 200, (b)
250, and (c) 300 ºC using elemental sulfur with different S/cation molar ratios ranging
from 1 to 8.
Figure S1. XRD patterns of the CZTS nanocrystal synthesized in ODE at temperatures of (a) 200,
(b) 250, and (c) 300 ºC using elemental sulfur with different S/cation molar ratios ranging from
1 to 8.
S5
XRD patterns of the CZTS nanocrystal synthesized in ODE with different Cu/(Zn+Sn)
molar ratio using elemental sulfur as anion source and OLA as solvent.
Figure S2. XRD patterns of the CZTS nanocrystal synthesized using CuxZnSn-(C18H33O2)6+2x
metal-oleate precursor with different Cu/(Zn+Sn) molar ratios of (a) 0.5, (b) 0.6, (c) 0.7, (d) 0.8,
(e) 0.9, (f) 1.0, (g) 1.1, and (h) 1.2. The nanocrystals were synthesized by injecting 2 ml
precursor solution (1 g metal-oleate dissolved in 1 ml ODE) into 0.4 g elemental sulfur in OLA
at 250 oC and aging for 30 min.
S6
Room temperature absorption spectra of CZTS nanocrystals with wurtzite (black) and
kesterite (red) structure
Figure S3. Room temperature absorption spectra of CZTS nanocrystals with wurtzite (black) and
kesterite (red) structure. Inset shows extrapolation of the spectra in the band edge region for
determination of the band gaps. All samples were synthesized using 1 g metal-oleate precursor
dissolved in 1 ml ODE. For wurtzite CZTS, the mole ratio for S/Cu2ZnSn(C18H33O2)10=4, and
reaction temperature is 250 oC. For kesterite CZTS, the mole ratio for
S/Cu2ZnSn(C18H33O2)10=1-2, and reaction temperature is 200 oC.
S7
Experimental and simulated XRD patterns of rod-like and rice-like CZTS nanocrystals
Figure S4. Experimental and simulated XRD patterns of (a) rod-like and (b) rice-like CZTS
nanocrystals synthesized at 250 oC after aging for 30 min.
S8